Reconstructing the climate of Mexico from historical records

There is a growing number of studies that use historical sources to reconstruct recent environmental change. In Mexico there are abundant sources of information that can be used to determine variations in the climate over the historical period. In this paper we draw together information from a variety of primary and secondary historical sources to reconstruct fluctuations in the climate of central Mexico over the last 600 years. The Aztecs are believed to have entered the Basin of Mexico during a period of severe drought. Wet conditions, however, characterized much of the Aztec (AD 1345-1521) and early colonial period prior to a return to drier conditions in the 1640s. Between 1640 and 1915, a series of severe droughts caused widespread devastation throughout central Mexico, particularly during the mid- to late 1700s and late 1800s. Since the early 1900s this region has experienced slightly wetter conditions. The climatic record from the Basin of Mexico is compared with proxy climatic data from two other areas in Mexico: a detailed lake-level curve from Lake Patzcuaro in central Mexico and the few tree-ring records from northern Mexico. Although the palaeoclimatic records from central Mexico are similar, there is greater divergence between the records from central and northern Mexico. In general, fluctuations in the climate over the last 600 years can be explained by changes in the relative strength of the summer 'monsoon', but it is possible that ENSO events can cause considerable differences in prevailing climate conditions in the northern and central parts of the country.